The present invention relates to electrographic imaging of the type wherein a printed image is created by a process which involves formation of an intermediate or latent charge image, development of the intermediate image, for example, by the application of a toner powder, and transfer of the developed image to a recording sheet. In particular, it relates to such imaging wherein the latent charge image is formed by the projection of charge carriers, i.e., ions, electrons or both, onto a latent imaging member, or wherein the latent charge image is otherwise formed at the surface such that closely contiguous points on the imaging member receive distinctly different levels of charge.
A problem exists in imaging systems of this type that the charged particles are projected onto a smooth and substantially uniform dielectric surface, and the latent image so deposited is subject to a certain amount of charge spreading and other electrical field effects that distort the intended charge distribution. Consequently, if an image is laid down without regard to these effects, it will result in a distorted print. Such distortions may include changing of line widths, disappearance of grey scale image portions, or distortion of the boundary regions separating image details of differing charge value.
Accordingly, it has become important to understand the sources of these distortions and to develop methods to avoid or correct them. This is especially true as such systems are applied to form print images with resolution above 200 dpi, or to form images with multiple tone levels or colors.